Such an actuator with satellite rollers is disclosed in particular in document FR 1 577 532.
In the field of ball or roller screws, it is known to apply a lubricant (oil, grease, solid lubricant), in order to improve the tribological characteristics thereof. This can involve an external application (for oil and grease in particular) or also the deposition (in particular on the screw) of a surface coating capable, through its wear, of progressively releasing solid lubricant particles. A solution is also known that makes use of self-lubricating intercalated bearings arranged between the balls or rollers.
With regard to rotolinear actuators with satellite rollers, if the intercalated bearings solution is not technically feasible, the solution of the application of an external lubricant (oil, grease) remains possible, and a solution consisting of forming a solid lubricant coating on the roller screws is also known.
However, these various solutions currently employed require the lubricant or the lubrication member to be replaced regularly, at intervals which can be longer or shorter but never cover the estimated lifetime of the actuator, and in particular, said replacement requires that the actuator be accessible.
These conditions cannot be fulfilled in certain fields of application of the actuators, as is the case in particular with electrical actuators for aircraft flight controls, the maintenance-free lifetime of which must cover the lifetime of the aircraft.
With regard to specific application to the electrical actuation of aircraft flight controls, the actuator requires a low rotation/translation ratio, hard and rigid constituent materials due to high contact pressures, as little friction as possible, and lifetime lubrication (i.e. for several tens of years); moreover, for safety reasons, the actuator must be reversible. These demands lead to the use of rotolinear actuators with screws having lubricated satellite rollers, in the knowledge that using a dry lubricant deposited on the screw and the techniques of progressive wear of operational parts cannot be envisaged due to the formation of residual particles that could result in seizing of the actuator, and that splash lubrication is undesirable and would be impractical to implement and unlikely to cover such a long period of time.
The purpose of the invention is therefore to propose an original technical solution capable of meeting the practical requirements with regard to the demands for long-term homogenous lubrication.